Nai-Chang Yuan

National University of Defense Technology, Ch’ang-sha-shih, Hunan, China

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Publications (20)13.99 Total impact

  • Shao-Yi Xie · Jing-Jian Huang · Wei-wei Wu · Nai-Chang Yuan
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    ABSTRACT: In this paper, a novel frequency selective surface (FSS) using random distribution method is investigated. This FSS can diffuse the reflected wave analogy to array antenna. The reflectivity of three-layer stacked cross patches are studied at first. Then an array of 20×20 FSS is constructed and simulated. Finally a 300mmx300mm three-layer random surface is fabricated and measured. More than 5dB RCS reduction in 7-20GHz is obtained from measurement. Both the simulation and measurement results demonstrate the validity of this design.
    No preview · Conference Paper · Aug 2014
  • Li-guo Liu · Jin-jun Mo · Yun-qi Fu · Nai-chang Yuan
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    ABSTRACT: The common predictions of angular glint are usually based on the condition of far-field hypothesis. However, computation of near field angular glint is very meaningful both in academic studies and engineering applications due to its huge impact on tracking error. This paper presents an analytic prediction of near field angular glint computing based on Graphic Electromagnetic Computing (GRECO), which is both in real time and on omission of the process of scattering center extraction. The condition that targets cannot be covered by radar beam is firstly considered, which makes the prediction of tracking error more complete. The correctness is validated by comparison between the simulated results and the theoretical ones of several models.
    No preview · Article · Apr 2014 · Dianzi Yu Xinxi Xuebao/Journal of Electronics and Information Technology
  • Shao-Yi Xie · Xiao-Fa Zhang · Jun Yang · Li-Guo Liu · Quan Wang · Nai-Chang Yuan
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    ABSTRACT: In this paper, an ultra-wideband, ultra-fast, fine resolution and compact digital instantaneous frequency measurement (DIFM) is proposed. The algorithm is implemented on the platform of Virtex-5 Field Programmable Grid Array (FPGA) from Xilinx. Due to only one high speed comparator with some relative circuits are needed, this DIFM can be blended in other digital system with compact size. The RocetIO GTP has been successfully introduced in this system for the interface with comparator. Thanks to the advantage of 1.46 GHz wideband, the large numbers of RF channels required in traditional solutions can be decreased. Comparing to traditional analog and digital method, this design is more flexible to reconfigure, easy to adjust, and with smaller size. The measurement results show that our invention is capable of detecting short wave pulse and continuous wave (CW) signal from DC to 1.46GHz with a major error within 1.25 MHz in less than 200 ns throughput time. This digital instantaneous frequency measurement (DIFM) system has been successfully used in radar systems.
    No preview · Article · Jan 2014 · IEICE Electronics Express
  • Hui Zhang · You-Quan Li · Xi Chen · Yun-Qi Fu · Nai-Chang Yuan
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    ABSTRACT: A novel kind of circular polarization and dual-frequency linear polarization microstrip antennas is proposed. The designs are based on the anisotropic property of the complementary split ring resonator. When the complementary split ring resonator is etched on the patch of the probe-fed microstrip antenna, the gap orientation asymmetric or symmetric to the current propagating direction will render the antenna to radiate circular polarization waves or dual-frequency linear polarization waves. Details of the experimental results compared with the simulated results are presented and discussed.
    No preview · Article · Nov 2009 · IEEE Transactions on Antennas and Propagation
  • Li-Guo Liu · Cheng-Lin Tian · Ping-Xing Chen · Nai-Chang Yuan
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    ABSTRACT: We derive an analytical lower bound on the concurrence for bipartite quantum systems with an improved computable cross norm or realignment criterion and an improved positive partial transpose criterion respectively. Furthermore we demonstrate that our bound is better than that obtained from the local uncertainty relations criterion with optimal local orthogonal observables which is known as one of the best estimations of concurrence.
    No preview · Article · Jun 2009 · Chinese Physics Letters
  • Qiu-Rong Zheng · Yun-Qi Fu · Nai-Chang Yuan
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    ABSTRACT: A novel compact electromagnetic band-gap (EBG) structure in a spiral shape is presented and investigated. This structure significantly enlarges the capacitance between neighboring elements. The simulations and experimental results have proved that the size of the spiral structure is only 30.9% of the conventional EBG structure. Two applications have been shown, including patch antenna with the spiral EBG structure and a double-element microstrip antenna array with low mutual coupling. The measured results show that a gain improvement over 3 dB and a significant reduction of cross polarization in H-plane are obtained. A 6 dB reduction of mutual coupling is achieved in a double-element EBG microstrip antenna array.
    No preview · Article · Jul 2008 · IEEE Transactions on Antennas and Propagation
  • You-Quan Li · Hui Zhang · Yun-Qi Fu · Nai-Chang Yuan
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    ABSTRACT: This letter investigates the application of EBG radar absorbing material (RAM) to asymmetric ridged waveguide slot antenna array to reduce its backward RCS. The EBG RAM is based on the mushroom-like EBG structure loaded with lumped resistances. A ridged waveguide slot antenna array with 4 times 10 slot elements was designed and built, part of the metal ground plane of the array is replaced with this EBG RAM. The measured results show that performance of the antenna array is preserved when EBG RAM is used. At working frequency the backward RCS of antenna array with EBG RAM has dramatically reduced than that of the common antenna array.
    No preview · Article · Feb 2008 · IEEE Antennas and Wireless Propagation Letters
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    Qiu-Rong Zheng · You-Ming Yan · Xiang-Yu Cao · Nai-Chang Yuan
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    ABSTRACT: In this paper a novel ultra-thin radar absorbent material (RAM) using HIGP is presented and investigated. Owing to the high impedance property of the HIGP, the thickness of the RAM is about several tenths of the centre wavelengthof the absorption band, considerably thinner than conventional absorbers. The absorption band of the RAM is about several hundred megahertz. In the new RAM, lumped resistances are soldered between the patches of mushroom-like high-impedance surface (HIGP). And the metal ground plane of waveguide slot antenna is covered by this new type of RAM. As compared to the slot antenna with a metal ground plane, the measured results show that the radar cross section (RCS) of waveguide slot antenna reduces significantly. This proves that the new HIGP RAM has a good radar absorbing characteristics. The simulations and experiment results have shown that the RCS of antenna is reduced by 7.9 dB and gain is only reduced by 0.9 dB.
    Preview · Article · Jan 2008 · Progress In Electromagnetics Research
  • Hui Zhang · You-Quan Li · Xi Chen · Yun-Qi Fu · Nai-Chang Yuan
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    ABSTRACT: A novel design of circular polarization microstrip patch antenna based on the complementary split ring resonator is evaluated numerically and experimentally verified. Unlike the previous application of its resonant performance, the non-resonant property of complementary split ring resonator is used as an asymmetric perturbation to excite the square microstrip patch antenna for a good circular polarization radiation. Good agreement is observed between the measurement and simulation results.
    No preview · Article · Jan 2008
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    Bao-Qin Lin · Qiu-Rong Zheng · Nai-Chang Yuan
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    ABSTRACT: A novel electromagnetic Band-Gap (EBG) scheme is presented for size reduction. The proposed structure can be considered as one kind of distorted Sievenpiper High Impedance Surface (HIS) in a spiral shape, while it becomes extremely compact in size. Its design is detailed in this study, and two experimental results are presented. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2186–2189, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22691
    Full-text · Article · Sep 2007 · Microwave and Optical Technology Letters
  • Feng-tao Wu · Nai-chang Yuan
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    ABSTRACT: Finite-difference time-domain (FDTD) algorithm was used to analyze ultra-wide-band (UWB) antenna array. Normalized radiation energy pattern was adopted to characterize the transmitting and receiving behaviour of (UWB) antenna array. Measured and simulated results indicate the planar TEM horn antenna array can be used in the practical UWB radar and communication system
    No preview · Conference Paper · Nov 2006
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    Bao-qin Lin · Qiu-rong Zheng · Nai-chang Yuan
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    ABSTRACT: A novel planar photonic band-gap (PBG) scheme is presented for size reduction, the proposed structure can be considered as a kind of distorted uniplanar compact-PBG (DUC-PBG) while being even more compact in size. Its design is detailed in this letter, and several experimental results are presented, the properties of the proposed DUC-PBG are examined, as compared with that of the conventional UC-PBG.
    Full-text · Article · Jun 2006 · IEEE Microwave and Wireless Components Letters
  • Qiu-Rong Zheng · Guo-hua Zhang · Nai-Chang Yuan
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    ABSTRACT: High impedance ground plane (HIGP) is a kind of electromagnetic band-gap (EBG) structure utilized as a ground plane for a single ridged wave-guide slot phased antenna array in order to improve its radiation characteristics. As compared to a solid metal ground plane, the results suggest that the HIGP can significantly improve the pattern of slot antenna array. The antenna gain is increased, the back lobes are reduced and the mutual coupling between two antenna arrays is reduced.
    No preview · Conference Paper · Jan 2006
  • Hui Zhang · Dun-bao Yan · Nai-Chang Yuan
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    ABSTRACT: A novel microstrip dipole antenna with H-shaped slot coupled is presented. Several design variations are discussed. Compared to the traditional microstrip dipoles with rectangular coupling slot, this antenna which occupies smaller volume is more suitable to be integrated with other microstrip antenna or active devices.
    No preview · Conference Paper · Jan 2006
  • Qiang Gao · Guo-hua Zhang · Dun-bao Yan · Nai-chang Yuan
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    ABSTRACT: High-impedance surface (HIS) is a kind of electromagnetic bandgap (EBG) structure utilized as a ground plane for two waveguide slot antennas in order to improve their radiation characteristics. As compared to a solid metal ground plane, the results suggest that a high-impedance ground plane (HIGP) can significantly improve the patterns of the slot antennas. The ripples in the E-plane patterns of the slot antennas with a metal ground plane are found to vanish, the back lobes are reduced, and the gains are increased.
    No preview · Article · Jan 2005
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    Dun-bao Yan · Chao Wang · Qiang Gao · Nai-chang Yuan
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    ABSTRACT: In this paper, a novel very compact inter-embedded artificial magnetic conductor (IE-AMC) structure is presented. Compared with conventional Sievenpiper AMC structure, for a desired band-gap frequency, the cell size of this novel IE-AMC structure is reduced about 70% with the same substrate used. Therefore, in practical application to microwave integrated circuits and antenna arrays for suppressing surface, for a given available space, more AMC structure cells can be used, and the performance of circuits and antennas can be improved more. On the other hand, low frequency surface wave band-gap which is applied to wireless communication band (GSM, PCS and ISM) can be obtained using IE-AMC structure.
    Preview · Article · Jan 2005 · PIERS Online
  • Qiu-Rong Zheng · Yun-qi Fu · Nai-Chang Yuan
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    ABSTRACT: A high impedance ground plane (HIGP) structure is used for asymmetric single ridged wave-guide slot antenna. As compared to a solid metal ground plane, the measured results proved that HIGP can significantly improve the radiation pattern. The radiation pattern become smoothly, the back lobe reduced and the gain is increased.
    No preview · Article · Jan 2005
  • Source
    Dun-bao Yan · Qiang Gao · Chao Wang · Nai-chang Yuan
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    ABSTRACT: In this paper, the patch size effect of mushroom-like Sievenpiper AMC (Artificial Magnetic Conductor) structure to reflection phase band-gap is studied. It is observed that the reflection phase band-gap is independent of the size in the direction perpendicular to polarization direction of incident plane wave. Consequently, strip- type AMC structure is introduced, and it is noticed this structure has independent reflection phase property and surface wave band-gap property. Compared with mushroom-like Sievenpiper structure, strip-type AMC structure is easier to design and fabrication, and has many advantages in antenna applications to circular patch antenna, plane spiral antenna and corrugated horn antenna etc.
    Preview · Article · Jan 2005 · PIERS Online
  • Guo-Hua Zhang · Yun-Qi Fu · Chang Zhu · Dun-Bao Yan · Nai-Chang Yuan
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    ABSTRACT: A high-impedance ground plane (HIGP) is used for a circular waveguide antenna. The benefits of using such a HIGP are related to the suppression of surface waves excited by the circular waveguide mouth, because the HIGP has a very obvious surface wave bandgap. Suppression or reduction of surface waves is expected to improve antenna efficiency and to bring a reduction of sidelobe level due to diffraction of the surface waves. In agreement with the expected result, the measured radiation patterns show that a 2 dB addition in the antenna gain and a 10 dB reduction in the back lobes, if the circular waveguide antenna working frequency is in the HIGP surface wave bandgap.
    No preview · Article · Feb 2003 · IEEE Antennas and Wireless Propagation Letters
  • Yun-Qi Fu · Guo-Hua Zhang · Nai-Chang Yuan
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    ABSTRACT: A novel coplanar waveguide with photonic bandgap structure is proposed and is implemented by etching holes in the ground plane with an open connected with the gap between strip line and ground plane. Simulation and measurement results show the existence of a bandgap.
    No preview · Article · Dec 2001 · IEEE Microwave and Wireless Components Letters